1. Field of the Invention
The present invention relates to a friction member assembly for a disc brake used in a disc brake apparatus for, for example, a railroad vehicle. More particularly, the present invention relates to an improvement for realizing a reduction in cost and promotion of productivity by alleviating a processing accuracy of parts.
2. Related Art
A disc brake apparatus is constituted by a disc rotor fixed to an axle, a torque receive plate arranged opposedly to the disc rotor, a brake caliper including an actuator for driving the torque receive plate to move to and from the disc rotor and fixed to a vehicle body frame, and a lining member integrated to a face of the torque receive plate on a side of the disc rotor. When the torque receive plate is moved to the side of the disc rotor and the lining member is pressed to the disc rotor, a brake force by a sliding friction is generated.
In a disc brake apparatus for a railroad vehicle, a disc rotor and a brake lining are large-sized. Therefore, when the lining member to be pressed to the disc rotor is formed by an integrated part, a noncontact region is increased owing to a waviness produced at the disc rotor by friction heat or the like. As a result, a stable friction area cannot be maintained and a stable braking characteristic is not provided.
Hence, in order to resolve the problem, disclosed in JP-T-10-507250 is a brake lining in which a number of pieces of second link plates are laid on a torque receive plate substantially by a plane shape. In addition, a number of pieces of first link plates are laid on the respective second link plates independently from each other and pivotably, and a number of pieces of lining members are arranged on the respective first link plates independently from each other and pivotably. The respective lining members on the respective first link plates are brought into contact with a disc rotor by moving the torque receive plate to the side of the disc rotor.
According to the brake lining having such a constitution, the respective lining members divided to be small are brought into contact with a surface of the disc rotor by following a waviness of the surface of the disc rotor by respectively individual pivoting operation. Therefore, a stable braking characteristic can be maintained by maintaining a stable friction area.
However, according to the brake lining described in JP-T-10-507250, a position of the lining member above the torque receive plate is restricted by a first universal joint for connecting the lining member pivotably to the first link plate by a spherical contact portion in either of a direction in parallel with the surface of the lining member and in a direction orthogonal to the surface of the lining member. Further, also a position of the second link plate on the first link plate is restricted by a second universal joint for connecting the first link plate pivotably to the second link plate by a spherical contact portion in either of the direction in parallel with the surface of the lining member and the direction orthogonal to the surface of the lining member.
As a result, all of brake torque operated to the lining members in braking are successively transmitted from the lining members to the first link plates and from the first link plates to the second link plates by way of the spherical contact portions of the universal joints, finally transmitted to the torque receive plate coupled with the second link plates. Therefore, unless the respective universal joints are solidly processed and the spherical contact portions of the respective universal joints are processed with high accuracy, there is a concern of concentrating an excessive load on portions of the universal joints to destruct.
However, since a number of portions of using the universal joints is large and therefore, when all the universal joints need to be constituted solidly and the spherical contact portions and counter side contact portions brought into contact with the spherical contact portions need to be processed with high accuracy, there poses a problem that cost of processing parts is increased, an increase in cost of the brake lining and a reduction in productivity are brought about.